[llvm] [libc-utils] disable target_compile_features (PR #121883)

[Brian Cain via llvm-commits]

androm3da wrote:

> The fix suggested in [#114591 (comment)](https://github.com/llvm/llvm-project/issues/114591#issuecomment-2452506483) seems more correct to me:
> 
> ```diff
> diff --git a/runtimes/CMakeLists.txt b/runtimes/CMakeLists.txt
> index 4a6b317a03f6..19518bc6d56e 100644
> --- a/runtimes/CMakeLists.txt
> +++ b/runtimes/CMakeLists.txt
> @@ -194,7 +194,7 @@ set(LLVM_TARGET_TRIPLE "${LLVM_DEFAULT_TARGET_TRIPLE}")
>  
>  if(CMAKE_C_COMPILER_ID MATCHES "Clang")
>    set(option_prefix "")
> -  if (CMAKE_C_SIMULATE_ID MATCHES "MSVC")
> +  if (CMAKE_CXX_COMPILER_FRONTEND_VARIANT MATCHES "MSVC")
>      set(option_prefix "/clang:")
>    endif()
>    set(print_target_triple ${CMAKE_C_COMPILER} ${option_prefix}--target=${LLVM_DEFAULT_TARGET_TRIPLE} ${option_prefix}-print-target-triple)
> ```
> 
> Can you try that out instead?

This change appears to have had no effect.  I have re-run the build now with more diagnostics `--trace-expand --debug-output --warn-uninitialized --warn-unused-vars --check-system-vars `. 

Here's the log with that additional context: [build_20.0.0.log.gz](https://github.com/user-attachments/files/18336631/build_20.0.0.log.gz) -- note that the beginning of the log includes all of the bootstrapping of the compiler, the runtimes build starts at `Running with expanded trace output on.`.



https://github.com/llvm/llvm-project/pull/121883